Optical Pulse Wave Velocity Measurement Apparatus
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Solution Overview
Problem
Existing biological-information obtaining apparatuses for determining pulse wave velocity (PWV) are large and unsuitable for daily use, requiring a significant setup to measure pulse wave propagation time across the entire body.
Innovation Solution
A compact biological-information obtaining apparatus using light-emitting means, an image sensor, and pulse-wave-velocity calculation means to calculate PWV based on time sequence changes in brightness values of captured images, allowing for downsized and portable PWV determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a phonocardiographic transducer and pressure sensor are used to determine PWV, then PWV measurement is possible, but the apparatus becomes large-scale and inappropriate for daily determination
Solution Approach 1:
The patent replaces the mechanical/electrical sensing system (phonocardiographic transducer and pressure sensor) with an optical imaging system. The image pickup device captures visual changes in blood vessel patterns caused by pulse wave propagation, and the processing unit calculates PWV based on the time difference of these visual changes between two locations. This substitution eliminates the need for complex mechanical sensors while maintaining measurement capability.
Solution Approach 2:
The patent uses visual images as a copy or representation of the physiological state. Instead of directly measuring mechanical pulse characteristics with sensors, the system captures optical images of blood vessel patterns, which serve as a copy of the physiological information. The processing unit then extracts temporal information from these image copies to calculate PWV, simplifying the measurement system.
2Measurement precision
If a large-scale apparatus is used to determine pulse wave propagation time over the entire body, then comprehensive PWV measurement is achieved, but portability and ease of use are reduced
Solution Approach 1:
The patent replaces complex mechanical measurement systems with a simple optical imaging system. The image pickup device can be a standard camera, and the processing unit uses software algorithms to extract physiological information. This substitution dramatically reduces the apparatus size and complexity, making it portable and suitable for daily use while maintaining accurate PWV measurement capability.
Solution Approach 2:
The patent introduces visual images as an intermediary medium between the physiological phenomenon (pulse wave propagation) and the measurement system. Instead of directly contacting the body with complex sensors, the system uses optical images as an intermediary to capture blood vessel pattern changes, which then serve as the basis for PWV calculation. This intermediary approach simplifies the overall system while maintaining measurement accuracy.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables efficient and portable measurement of PWV, reducing the need for large-scale apparatuses and improving accessibility for daily use while maintaining accurate calculations.
Implementation Method 1
light-emitting means for emitting light, an image sensor for capturing images, in time sequence, obtained by irradiating a living body with the light emitted and by causing the light to be transmitted through or reflected by the living body
Data Source
AI summary
A biological-information obtaining apparatus includes a light-emitting unit, an image sensor configured to capture images, in a time sequence, relating to a living body, and a lens. The apparatus also includes an extreme-occurrence-time obtaining unit configured to obtain times T1 and T2 at which extremes occur in time sequence with respect to brightness values of a first region and a second region, respectively, of each of the captured images. The apparatus further includes a pulse wave velocity (PWV) calculation unit configured to calculate a pulse wave velocity according to the equation, P=(Y×L/f)/(T2−T1), where Y represents a distance on the image sensor, the distance corresponding to a distance between the first region and the second region, f represents the focal length of the lens, and L represents a distance between the lens and the living body.